The present invention relates generally to new and novel improvements in direct drive variable displacement pumps. More particularly, the present invention relates to direct drive variable displacement pumps that are capable of providing high pressure fluid flow for use in high-pressure fluid cutting, abrasive-fluid cutting, cleaning and similar applications.
In the past, to induce high pressure on fluids, such as above 15,000 pounds per square inch, intensifier pumps have typically been used. Intensifier pumps provide the capability of multiplying a relatively low pressure fluid, using area ratios, into a relatively high pressure fluid. Intensifier pumps are sometimes capable of providing a fluid pressure increase on the order of several magnitudes and presently some intensifier pumps are providing fluid pressures as high as 200,000 pounds per square inch.
For high-pressure fluid cutting, abrasive-fluid cutting, cleaning and similar applications, intensifier pumps capable of providing a fluid pressure on the order of 60,000 pounds per square inch are commonly used. Traditional crank type pumps are currently capable of providing a fluid pressure on the order of 40,000 pounds per square inch and are expected to be capable of providing a fluid pressure on the order of 55,000 pounds per square inch or higher in the not to distant future. Such high-pressure crank pumps are generally less complex, smaller, more efficient, less expensive, provide a higher fluid delivery to size ratio, and provide a more constant flow delivery than comparable intensifier pumps.
However, traditional high-pressure crank pumps also have their limitations. One significant limitation is that in fluid jet applications, traditional high-pressure crank pumps generally have a fixed displacement that requires either speed regulation to control the fluid flow delivery or some other way of unloading excess fluid flow, such as by using unloaders, relief valves and similar devices. This limitation is not present in intensifier pumps that provide only the necessary flow demand while maintaining the required pressure.
Accordingly, an object of the present invention is to provide direct drive variable displacement pumps that provide many of the advantages of traditional crank type pumps and intensifier pumps while eliminating many of their limitations.
Another object of the present invention is the provision of direct drive variable displacement pumps that are suitable for use in fluid cutting, abrasive-fluid cutting, cleaning, and similar application.
Yet another object of the present invention is the provision of direct drive variable displacement pumps that are capable of being used with non-lubricating fluids, such as water.
Yet another further object of the present invention is the provision of direct drive variable displacement pumps that are capable of providing constant fluid pressure, constant fluid flow, and constant horsepower.
These and other objects of the present invention are attained by direct drive variable displacement pumps that provide variable displacement wherein a swashplate pivots and changes the angle position in the direct drive variable displacement pumps. The swashplate is also capable of changing the stroke length of pistons in such direct drive variable displacement pumps and rotation of a rotating shaft is converted into axial or radial movement. In direct drive variable displacement pumps in accordance with the present invention, plungers and their respective plunger housings do not rotate relative to the rotating shaft while the swashplate rotates with the rotating shaft. In addition, hydraulic control pistons are preferably used to change the angle of the swashplate and these hydraulic control pistons rotate with the rotating shaft. A first preferred embodiment of a direct drive variable displacement pump disclosed herein is an axial displacement type direct drive variable displacement pump while a second preferred embodiment of a direct drive variable displacement pump disclosed herein is a radial type direct drive variable displacement pump.
Other advantages and novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings.